Head and jaw releasable fastenings



July 1, 1969 P. w. ,JEFFfiIES 3,453,013

HEAD AND JAW RELEASABLE FASTENINGS Filed April 6. 1967 United States Patent US. Cl. 29218 2 Claims ABSTRACT OF THE DISCLOSURE A head and jaw fastening in which the jaws are spring biased towards a closed position and are provided with interlock portions to establish a predetermined angular position of the jaws when the head is withdrawn, the jaws together with their interlock portions being identical with each other.

Background of the invention Field of the inventi0n.This invention relates to releasable fastenings of the kind which comprise an element having a head portion and a neck portion, the said element being adapted to be secured to a member, and a pair of jaws spring pressed towards a partly closed position in which their inner faces define an opening shaped to engage interlockingly the said head portion, the said jaws being adapted to be secured to another member to which the first said member is required to be releasably fastened, the head portion and jaws being so shaped that the former can be pressed between the latter, opening them against the said spring pressure, and upon being pressed fully home between the jaws permitting them to return to the said partly closed position with the said neck portion disposed between their ends so that the head portion cannot be withdrawn by the same path except against the said spring pressure. Fastenings of the kind are hereinafter referred to as fastenings of the kind specified.

Description of the prior art-In British patent specification Ser. No. 637,774 a fastening of the kind specified is described and claimed, the jaws of such fastening having complementary interfitting faces adapted when in engagement to prevent pivotal movement of the jaws as a rigid unit, and to determine positively the position of both jaws considered as a rigid unit in relation to an attachment element, as well as their position relatively to each other when partly closed.

The provision of dies suitable for the formation of jaws by a pressing operation or the provision of metal die parts which collectively form a mould cavity suitable for the formation of jaws from a synthetic resin injected or otherwise charged into such cavity represents the major cost involved in manufacturing a fasteinng of the kind specified, and such cost is materially reduced when, in accordance with the present invention, each jaw can be so pressed from the same dies or so moulded in the same mould cavity.

Summary of the invention (1) a first part disposed at one side of a median plane which lies at right angles to the pivotal axis of the jaws, and

ice

(2) a second part of a shape complementary to that of the first part and disposed on the other side of said median plane, to mate with said first part of said interlock portion of the other of said jaws to hold said jaws collectively in a predetermined angular position relatively to the attachment element when the head portion is withdrawn from between the jaws, and

(c) The interlock portion and the remaining portions of the one jaw being identical with the interlock portion and the remaining portions of the other jaw.

Brief description of drawings The invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is an exploded perspective view showing the various componnets of one construction of the fasten- 111g,

FIGURE 2 is a view in side elevation and partly in cross-section of the same fastening assembled, the heavy arcuate double lines indicating a cover, and

FIGURE 3 is a view in side elevation of another construction of the fastening.

Description of the preferred embo'diment In the construction shown in FIGURES l and 2 one element 10' of the fastening comprises an attachment plate 11 suit-ably provided with holes 12 for the reception of fixing screws, the plate having at or near its centre a head portion 13 formed integrally with the plate and joined thereto by means of a neck portion 14. The holes 12 are in the form of elongated slots having their lengths disposed longitudinally of the plate 11 which is generally rectangular in shape with the head portion 13 disposed midway between the ends.

The head portion 13 is of cylindrical form and the neck portion 14 merges smoothly with the surface of the head portion and is narrower than the diameter of the head portion, and presents side faces 15 which are parallel to the axis of the head portion and of concave crosssection.

Alternatively the head portion 13 could have a wedgeshaped leading face and an undercut base portion oonstituting the neck, the wedge and base portions merging through rounded corners.

This element 10 of the fastening may be formed from metal as a casting or it may be formed as a moulding from a synthetic resin. Alternatively it may be formed as a pressing from sheet metal.

The other element 20 of the fastening also comprises an attachment element in the form of a plate 21 which is of generally rectangular shape provided with suitable holes 22 adjacent to each corner for the reception of fixing screws and having a pair of upstanding lugs 23 extending from opposite longitudinal edges of the plate at right angles to one of the faces thereof.

Each of the lugs 23 is formed with a pair of circular openings 2-4 spaced apart parallel to the plane of the plate 21 and slightly above it, that is to say on the side to which the lugs 23 project.

Two jaws 30 are each connected to the attachment plate 21 by a pivot 25 extending through the openings 24 and a cylindrical bore 37 in the jaw 30.

The ends of the jaws near to the bores 37 are partly accommodated within a centrally disposed aperture 27 in the plate 21.

The inner faces 31 of the jaws 30 are collectively of a shape in cross-section which is complementary to that of the head 13 of the other element 10 of the fastening,

in this case the inner faces 31 of the jaws 30 being of concave cylindrical form. In the partly closed position of the jaws the shape and size of the opening defined by their inner faces are such as to engage closely around the head portion.

The ends 32 of the jaws remote from the associated pivot pins 25 are prevented from closing by means of an interlock portion on each jaw cooperating with an interlock portion on the other jaw, such portions being disposed adjacent to the pivot pins which extend through openings running one side of each jaw to the other side thereof.

Each such interlock portion is asymmetrical about a median plane at right angles to the attachment plate and to the pivot pins. Thus, on one side of the median plane each interlock portion includes a projecting male part 33 of triangular shape in a cross-sectional plane parallel to the median plane, while on the other side of the latter is a female part 34 V-shape in cross-section, the included angle being equal or approximately equal to the apex angle of the male part 33. Dimensionally these two parts are such that when the interlock portions are placed face-to-face, as is the case when the two jaws 30 are assembled with the attachment plate 21, they can interfit with each other.

Such interfitting relation is effected under pressure from spring means, and for this purpose the outer face of each jaw is provided with an integrally formed lug 35 projecting therefrom parallel or approximately parallel to the plate 21 of the attachment element.

Between the plate 21 and each lug 35 is disposed a coiled compression spring 26. Such springs are retained or located in position by, for example, forming an appropriately dimensioned recess or a projection on the face of the lug opposed to the plate of the attachment element, whilst a recess or projection is also formed in the latter in each case to receive an end portion of the spring. In the construction illustrated in FIGURES l and 2 the springs 26 are retained by projections 36 on the lugs 35 and by recesses 27 in the plate 21.

The springs tend to move the two jaws towards a closed position, and such movement is limited to abutment of the interlock portions which, when engaged, serve to prevent angular movement of the two jaws as a unit about the axes of the pins.

The jaws are thus centralised relatively to the attachment element even though the springs may differ in strength or dimension, or even though one of them may become weakened or broken in service.

Furthermore if, due to inaccurate fitting on the article to which the fastener is applied, the head portion should engage one of the jaws during closing of the fastener before it engages the other jaw the cooperation of the interlock portions of the two jaws results in both of the springs being stressed so that both are eventually operative to retain the head between the two jaws.

As a possible alternative one pair of openings 24 through which one of the pivot pins passed could be disposed at a greater distance from the attachment plate 21 than the other pivot pin, so that under the pressure of the springs the jaws collectively establish a noncentralised but predetermined angular position relatively to the attachment plate when the head portion is removed from between the jaws.

The extent to which the jaws can close together is such that a gap is always left between the free ends of the jaws to facilitate entry of the head element.

The interlock portions and the remaining portions of the jaws being identical permit formation of the jaws from a synthetic resin being moulded in a mould cavity defined by metal die parts.

The attachment element, that is to say the plate with the lugs, can also be formed as a moulding from said synthetic resin.

The synthetic resin selected for forming the element of the fastening incorporating the head portion, and for forming the jaws should afford high strength especially in relation to shock loads, good resistance to abrasion,

4 and good corrosion resistance. One suitable material is that known as nylon: either plain or embodying a reinforcing substance, for example glass fibre. Alternatively a polyacetal resin such as that known as Delrin may be used.

The pivot pins can also be formed as a moulding from said synthetic resin, and can be retained in the opening 24 by upsetting their ends after assembly. Any of the synthetic resins mentioned in the last foregoing paragraph may be employed.

Any of the foregoing components may alternatively be formed from metal either as sand mould castings, die castings, hot brass pressings, steel forgings or sheet metal pressings.

The element 20 may be provided with a cover 40, in FIGURE 2, which is of generally rounded cross-section as viewed in side elevation and approximately rectangular in end elevation. The cover 40 has an opening 41 through which the jaws 30 protrude and is detachably secured to the plate 21 by the engagement of inturned lips 42 at the edge of cover 40 with ribs 28 at the ends of plate 21. Any other suitable manner of securement, e.g., by screws passing through screw holes in lugs at each end of the cover could be used.

The construction shown in FIGURE 3 is generally similar to that shown in FIGURES l and 2 and like reference numerals have been used for like parts.

In this construction, however, the jaws 30 extend from one side of the attachment plate 121 through an aperture to the other side of plate 121 where they are connected to lugs 23 by pivot pins 25.

Springs 26 are retained in position by projections 36 on lugs 35 and by deep recesses within stems 50.

The aperture in plate 121 is enlarged as compared with aperture 27 in FIGURE 1 so as to permit movement of the jaws 30 and allow springs 26 to extend through plate 121.

In use of this construction a recess would be provided for the accommodation of stems 50 and lugs 23 in the manner to which the plate 121 is to be attached.

As an alternative to the compression springs 26, each jaw could be pressed towards the partly closed position by a torsion spring.

In a further construction (not shown) the attachment element for the jaws comprises a generally box-like housing provided with an attachment plate having an opening to allow the head to pass into the interior to engage between the jaws. When the fastening is in use, the housing would be accommodated within a recess in the member on which it is required to be carried with the apertured wall of the housing flush with a surface of such member.

Springs biassing the jaws towards a closed position extend between lugs formed on the jaws and the wall of the housing opposed to the attachment plate.

I claim:

1. In a releasable fastening comprising an element having a head portion and a neck portion, the said element being adapted to be secured to a member, and a pair of jaws spring pressed towards a partly closed position in which their inner faces define an opening shaped to engage interlockingly the said head portion, the jaws being adapted to be secured to any member to which the first said member is required to be releasably fastened, the head portion and jaws being so shaped that the former can be pressed between the latter, opening them against the said spring pressure, and upon being pressed fully home between the jaws permitting them to return to the said partly closed position with the neck portion disposed between their ends so that the end portion cannot be Withdrawn by the same path except against said spring pressure, the improvement comprising:

(a) pivot means separately connecting each jaw at its inner end to an attachment element, the pivotal axes of the jaws being parallel to each other and spaced apart,

(b) an interlock portion on each of said jaws, each such interlock portion including:

(1) a first part disposed at one side of a median plane which lies at right angles to the pivotal axis of the jaws, and

(2) a second part of a shape complementary to that of the first part and disposed on the other side of said median plane, to mate with said first part of said interlock portion of the other 10 of said jaws to hold said jaws collectively in a predetermined angular position relatively to the attachment element when the head portion is withdrawn from between the jaws, and (c) the interlock portion and the remaining portions of the one jaw being identical with the interlock portion and the remaining portions of the other jaw. 2. A fastening according to claim 1 wherein: (a) each said first part is a projection of triangular,

or approximately triangular, shape in a crosssectional plane parallel to said median plane, and

(b) each said second part is a recess of V-shape or approximately V-shape in a cross-sectional plane parallel to said median plane.

References Cited UNITED STATES PATENTS 839,876 1/1907 Naery 292-18 1,246,492 11/ 1917 Thiele 24-254 2,459,970 1/ 1949 Smith 24-252 X 2,460,162 1/1949 Alsop et a1 24-137 FOREIGN PATENTS 637,774 5/ 1950 Great Britain.

DONALD A. GRIFFIN, Primary Examiner.

US. Cl. X.R. 

